I use magnets for them to keep them in place. I use thin magnet sheets and they work really well for them and they don't move at all. I then place the label from the pot on them, it's pretty much the same process that I use for depotting shadows, LOL
Oh, the cool thing is, because there is a little space usually on on side of the MES, I have found that I usually don't need heat to depot them. I just go to the side that there is space, place a needle or small knife push all the way down and start to lift. Sometimes you have to start to lift and then reposition the needle or knife to under the porcelain and then just totally lift it out. It is really easy to do.